Getting a lab setup to test out topology before burying fiber and getting ahead of ourselves.
We have one Dell PowerConnect 2724 acting our core switch and two 2824s acting as a switch for two buildings. Currently using a TP-LINK TL-R600VPN as our router. Planned layout explained here Need some direction on multi-building network
Picked up 6 multimode modules from FS.com (spoke with a rep to pick compatible modules) and 6 multimode LC to LC fiber cables to get our lab setup.
After some trial and error, we ended up with the 2724 not linking with either 2824. However we can get the two 2824s to link with each other.
Odd thing is however is that we have a link light on both sfp ports on the 2724 but no lights on each respective 2824 sfp port. Got this far by disabling auto-negotiation for the combo ports but nothing else is obvious. Swapped modules around and cables. Not sure what is going on.
Here is the connection mapping on the photo below:
2724:23 ==> 2824[1]:23
2724:24 ==> 2824[2]:24
2824[1]:23 ==> 2824[2]:23
No idea with your specific hardware but some fibre/sfp things that have bitten me in the past:
make sure your switches can both run the (specific) SFP at the desired link speed. some CISCO switches for example can’t run gig SFPs at 100 meg, others can with the same SFP.
make sure your switches have firmware that actually supports the SFP module. CISCO at least need a driver in the IOS to run the specific SFP module. Think of them like add-in cards. Too old firmware = no driver = no SFP module support
make sure your fibre patch leads are the correct polarity (though given you can link two of the same model together this is probably not it). If not, you can swap the pair on one end of the cable.
also (maybe obvious) - make sure your patch leads are multimode for multimode and single mode for single mode. using incorrect cable may somewhat work but cause all sorts of random shit (though your pic looks like they’re OM3 patch leads)
Given what you wrote above, my bet is on incompatibility between the firmware and the SFP module on your 2724 model switch perhaps. Check firmware versions and HCL…
SFPs may just look like media converters, but they actually need to be driven by the switch and without the appropriate firmware they won’t work.
There is an Optical Transceiver Diagnostics page. When a link light is present on the port, the diagnostics checklist is all marked with green checkboxes.
Sure did. Blew out the sfp slots on the switches like an old NES cartridge lol.
Did reset the switches, yes. There were some LAG settings still present. From some research, if it senses a sfp module then it will switch to that from the copper port. Nothing in the manual that mentions anything special with the sfp ports.
Gonna call it. Switches work as we would expect when using copper cabling to link them all up. Just not when we use the fiber cabling. Going to assume that was the case for these switches to show up on CL for cheap.
We are going to go with unifi 8 port POE switch for the time being and use the fiber modules in 1G. Then in time we will make our move to 10G and move to the 48 port switch for sfp+. Totally overkill but that is only sfp+ supporting model unifi has at the moment. Hopefully a lower number port will be in production when we are ready to move to 10G.
Some ports are dual RJ45/SFP+ on the same switch-port.
I.e., they are both say, Gigabit1/47 but only one hole will work at a time as they are the same port internally.
Did you try clearing the LAG settings? It is possible that the port won’t come up if it can’t establish the link aggregation protocol on the port connected…
Yep, wiped the whole config file on each. Was following a few Dell forum threads last night that were very very close to our issue, checked their settings against ours and changed some things but nothing fully worked. I think the sfp ports themselves have some issue.
I would get N/S (not supported) on the Optical Transceiver Diagnostics page for say, Transmitter Fault, on one 2824 but have voltage and temp readings. The other 2824 would act as if the module wasn’t even installed even though I have a link light. Same results with swapping around modules.
The 2724 however showed all clear on their diagnostics page so I suspect that guy would work properly. Just not the 2824s that we have.
I am not an electronics guy, but maybe contact cleaner? I think it evaporates, etc. Obviously turn the switch off first so you don’t short anything out.
bumping this back up
just a quick question that may seem silly but are the cables routed correctly (transmitter to reciever)?
sometimes a simple thing like that can throw you!
and if you have solved the issue Please post the fix and mark it as solved
Pretty much ditched the switches we had (got them in a CL package deal) so it was all cheap to get a little lab going.
When we are ready to do fiber between buildings (10G at that point) we’ll probably be going with the XG switches from UniFi since we have their security gateway and access points.
We just ran cat6 and coax between our server closet in our shop and two buildings. I have a thread on that one that I will update with some photos.
yeah a lot of people have problems when first installing fibernet
the nic’s transmit and receive ports are a laser(transmit) and photocell (receiver)
and are not able to auto negotiate if a cable is reversed
some prefabbed cables were indexed and interlinked so they could not be reversed but many weren’t
when we had to run fiber at the plant we had to be careful not to install the wrong connector on the cable.
I got modules and prefabbed cables from fs.com for the lab test so I was counting on that to all be correct.
It was just odd how the link/activity lights where consistent on each switch. Like there was some config issue in the switch. Everything was configured correctly and matched settings where the ports where showing a proper link.
Just chalked it up to the reason I was able to get 5 switches for $50.
